Radiation is widely used for medical treatment. The primary radiation source is gamma or high energy x-rays. Thermal, epithermal, and high energy neutrons are also used.
It is critical that the amount and location of the radiation delivery be controlled as closely as possible. An error in intensity can either result in excessive tissue damage, or result in not accomplishing its intended purpose. An error in location can inadvertently cause damage to healthy tissue and organs, sometimes to critical organs such as eyes, brain, glands, etc, and cause severe debilitating damage and even death.
One method of estimating dose to a patient receiving thermal and epithermal neutron therapy is to insert a gold needle into the patient and then perform a partial exposure. The partial exposure is typically calculated to terminate at about the half-way point. The dose is generally terminated by the operator at the half-way point by turning off the source of radiation, or by closing off the radiation source. At that time the gold needle is removed and a radiation count is taken and dose calculations performed. The activation of the gold needle is assumed to be proportional to exposure to the gold needle. From the count rate taken on the gold needle the estimated dose received by the patient is calculated. Then the operator continues the radiation exposure to the full prescribed dosage. A disadvantage of this method is the invasiveness. In addition, gold needles may not be suitable for certain types of radiation.
Another method of estimating patient dose is with a stimulated phosphor. Disadvantages of using a stimulated phosphor include use of an infrared laser or other infrared light source to heat the phosphor. Since an infrared source is required, real-time measurement is not practical.
Another approach to estimating dose is the use of a phantom prior to irradiation. A phantom is in essence a model made of "equivalent material" to the object to be examined. A limitation of this method is that it is indirect and is subject to variation in the patient(s) compared to the phantom.
Accordingly, there is a need for an apparatus for measuring a non-invasive, real-time actual patient radiation dose.